which is why a trio of big brains from nasa, apole low 9 astronaut rusty schweker, rob lou and scott hubbard have become the astronaut hunters, launching their own mission to find an asteroid that are on a collision course with our world. >> this asteroid is important because it's a wake-up call that we should be looking out there. these things do hit the earth. >> reporter: the last near disaster was averted by pure luck. it was 1908 and a huge asteroid made a direct hit. fortunately into siberia, where a thousand miles of trees and wildlife were decimated. just imagine if the bull's eye were new york or chicago? >> if i very large asteroid were to hit, miles across, it would probably create the same kind of disaster that wiped out the dinosaurs. >> reporter: amazingly, no one knew da-14 was headed our way until a spanish dentist and amateur astronomer randomly discovered this grainy proof a year ago. >> of all the asteroids that are out there that come near the earth and can do harm if they hit the earth, we only know 1% now. 99% of them, we don't even know where they are. >> repor